Synthesis and crystal structure of uranium(IV) complexes with calix[n]arenes (n = 4, 6 and 8): mononuclear, polynuclear and 1D polymeric species

Reactions of UCl4 with calix[n]arenes (n = 4, 6) in THF gave the mononuclear [UCl2(calix[4]arene - 2H)(THF)2].2THF (.2THF) and the bis-dinuclear [U2Cl2(calix[6]arene - 6H)(THF)3]2.6THF (.6THF) complexes, respectively, while the mono-, di- and trinuclear compounds [Hpy]2[UCl3(calix[4]arene - 3H)].py (.py), [Hpy](4)[U2Cl6(calix[6]arene - 6H)].3py (.3py), [Hpy]3[U2Cl5(calix[6]arene - 6H)(py)].py (.py) and [Hpy]6[U3Cl11(calix[8]arene - 7H)].3py (.3py) were obtained by treatment of UCl4 with calix[n]arenes (n = 4, 6, 8) in pyridine. The sodium salt of calix[8]arene reacted with UCl4 to give the pentanuclear complex [U{U2Cl3(calix[8]arene - 7H)(py)5}2].8py (.8py). Reaction of U(acac)4 (acac = MeCOCHCOMe) with calix[4]arene in pyridine afforded the mononuclear complex [U(acac)2(calix[4]arene - 2H)].4py (.4py) and its treatment with the sodium salt of calix[8]arene led to the formation of the 1D polymer [U2(acac)6(calix[8]arene - 6H)(py)4Na4]n. The sandwich complex [Hpy]2[U(calix[4]arene - 3H)2][OTf].4py (.4py) was obtained by treatment of U(OTf)4 (OTf = OSO2CF3) with calix[4]arene in pyridine. All the complexes have been characterized by X-ray diffraction analysis.     

Uranium(IV) complexes of calix[n]arenes (n = 4, 6 and 8)

Reaction of UCl4 with calix[n]arenes (n = 4, 6 and 8) in THF or pyridine gave the mononuclear [UCl2(calix[4]arene--2H)(THF)2], bis-binuclear [U2Cl2(calix[6]arene--6H)(THF)3]2 and trinuclear [Hpy]6[U3Cl11(calix[8]arene--7H)] complexes, respectively, which are the first U(IV) complexes of O-unsubstituted calixarenes.     

Selective complexation of uranium(III) over lanthanide(III) triflates by 2,2':6',2"-terpyridine. X-Ray crystal structures of [M(OTf)3(terpy)2] and [M(OTf)2(terpy)2(py)][OTf](M = Nd, Ce, U) and of polynuclear mu-oxo uranium(IV) complexes resulting from hydrolysis

Reactions of Ln(OTf)3(Ln = Ce, Nd) or [U(OTf)3(dme)2](OTf = OSO2CF3, dme = dimethoxyethane) with 2 mol equivalents of 2,2':6',2"-terpyridine (terpy) in pyridine or acetonitrile led to the quantitative formation of the bis(terpy) complexes which crystallized as the discrete cation-anion pairs [M(OTf)2(terpy)2(py)][OTf] x 0.5py from pyridine or neutral derivatives [M(OTf)3(terpy)2] x nMeCN from acetonitrile (M = Ce, Nd, U). The crystal structures of these complexes show the differences in the M-O bond lengths to follow the variation of the ionic radii of the metals, while the U-N(terpy) and U-N(py) bonds are shorter than those expected from a purely ionic bonding model. The better affinity of terpy for U(III) over Ce(III) and Nd(III) was evidenced by the thermodynamic parameters (K, DeltaH, DeltaS) corresponding to the equilibrium between the bis- and tris(terpy) complexes in acetonitrile. Hydrolysis of the bis(terpy) compounds followed different courses; whereas the aquo compound [Ce(OTf)2(terpy)2(H2O)][OTf] crystallized readily from pyridine, the uranium complexes [UX2(terpy)2(py)]X (X = I, OTf) were oxidized into the tri- and tetranuclear mu-oxo U(IV) compounds [{UI(terpy)2(mu-O)}2{UI2(terpy)}]I4 x 2MeCN x H2O and [{U(OTf)(terpy)2(mu-O)(mu-OTf)U(terpy)}2(mu-OTf)2(mu-O)][OTf]4 x py x MeCN. The crystal structures of these first examples of uranium(IV) compounds with terpy ligands show the almost linear arrangement of the metal atoms.     

Synthesis and crystal structure of tetra- and hexanuclear uranium(IV) complexes with hexadentate compartmental Schiff-base ligands

Treatment of UCl4 with the hexadentate Schiff bases H2Li in thf gave the expected [ULiCl2(thf)] complexes [H2Li=N,N'-bis(3-methoxysalicylidene)-R and R = 2,2-dimethyl-1,3-propanediamine (i= 1), R = 1,3-propanediamine (i= 2), R = 2-amino-benzylamine (i= 3), R = 2-methyl-1,2-propanediamine (i= 4), R = 1,2-phenylenediamine (i= 5)]. The crystal structure of [UL4Cl2(thf)] (4) shows the metal in a quite perfect pentagonal bipyramidal configuration, with the two Cl atoms in apical positions. Reaction of UCl4 with H4Li in pyridine did not afford the mononuclear products [U(H2Li)Cl2(py)x] but gave instead polynuclear complexes [H4Li=N,N'-bis(3-hydroxysalicylidene)-R and R = 1,3-propanediamine (i= 6), R = 2-amino-benzylamine (i= 7) or R = 2-methyl-1,2-propanediamine (i= 8)]. In the presence of H4L6 and H4L7 in pyridine, UCl4 was transformed in a serendipitous and reproducible manner into the tetranuclear U(iv) complexes [Hpy]2[U4(L6)2(H2L6)2Cl6] (6a) and [Hpy]2[U4(L7)2(H2L7)2Cl6][U4(L7)2(H2L7)2Cl4(py)2] (7), respectively. Treatment of UCl4 with [Zn(H2L6)] led to the formation of the neutral compound [U4(L6)2(H2L6)2Cl4(py)2] (6b). The hexanuclear complex [Hpy]2[U6(L8)4Cl10(py)4] (8) was obtained by reaction of UCl4 and H4L8. The centrosymmetric crystal structures of 6a.2HpyCl.2py, 6b.6py, 7.16py and 8.6py illustrate the potential of Schiff bases as associating ligands for the design of polynuclear assemblies.     

Reductive coupling of carbodiimides with metallic lithium: a new route to metal oxalamidino complexes

Carbodiimides (RN)2C were reductively coupled with Li powder into [{Li(py)2}2(mu-C2N4R4)] (R = p-tolyl) (1) and [{Li(THF)}2(mu-C2N4R4)] (R = Cy) (2), and 2 reacted with UCl4 to give [Li(py)4]2[{UCl4(py)}2(mu-C2N4R4)] (R = Cy) (3); the crystal structures of 1 and 3 x 2py, the first oxalamidino compounds of an alkali metal and of a 5f-element, have been determined.     

Synthesis and X-ray structure of the [{Fe3(CO)9(micro3-O)}2H]3- trianion: dimerization of a metal carbonyl cluster via formation of an exceptionally short hydrogen bond

The synthesis, structure and characterization of the [{Fe3(CO)9(micro3-O)}2H]3- trianion in its [Cs(THF)0.33]+ and [NEt4]+ salt are reported. The title dimeric cluster has been obtained by protonation in water or in organic solvent of the [Fe3(CO)9(micro3-O)]2- dianion to the hydroxo [Fe3(CO)9(micro3-OH)]- derivative and crystallization. The solid state structure of [Cs(THF)0.33]3[{Fe3(CO)9(micro3-O)}2H] is based on ionic packing of [Cs(THF)0.33]+ cations and [{Fe3(CO)9(micro3-O)}2H]3- trianions. The fractional formula is due to the particular packing of Cs+ cations, which are at the vertices of fused cuboctahedral and trigonal antiprismatic polyhedrons. Each cuboctahedron encapsulates a [{Fe3(CO)9(micro3-O)}2H]3- trianion, whereas each trigonal antiprism encapsulates a THF molecule. The possibility that the structure of the [{Fe3(CO)9(micro3-O)}2H]3- trianion could be affected by its confinement in the cuboctahedral cage of Cs+ ions and the heavy disorder of the THF molecule urged a further structural determination of the trianion with a completely different cation. The corresponding [NEt4]3[{Fe3(CO)9(micro3-O)}2H] salt has been, therefore, prepared and structurally characterized. The [{Fe3(CO)9(micro3-O)}2H]3- trianion displays an identical structure and almost coincident molecular parameters in both salts. Its most notable feature is represented by the unique hydrogen atom symmetrically bridging the micro3-O atoms of two different [Fe3(CO)9(micro3-O)]2- molecules and displaying one of shortest O...H...O interaction so far reported in organic, inorganic and organometallic literature. The structure of [Cs(THF)]2[Fe4(CO)13], which has been obtained as a by-product of the synthesis of [Cs(THF)0.33]3[{Fe3(CO)9(micro3-O)}2H], is also briefly reported.     

Group 13 organoderivatives supported on a metallic oxide model

The [{TiCp*(micro-O)}3(mu3-CH)] (1) metalloligand, (Cp* = eta5-C5Me5), coordinates in a 1:1 ratio to [AlMe3] or 9-BBN to give [{Me3Al}{(mu3-O)(mu-O)2(TiCp)2(TiCp)3(mu3-CH)}](2) or [{(C8H14)B}(mu-H) {(mu3-O)(mu-O)2(TiCp*)3(mu3-CH)}](4), respectively, partial hydrolysis of 2 leads to the new hydroxo-aluminium derivative [{MeAl} {(mu-OH)(mu3-O)}2{(mu-O)2(TiCp*)3-(mu3-CH)}2](3).     

New efficient synthesis of [Ul4(meCN)4]. X-ray crystal structures of [Ul2(MeCN)7][Ul6], [Ul4(py)3], and [U(dmf)9]l4

Reaction of UCl4 and excess Me3Sil in acetonitrile provides a convenient route to [Ul4(MeCN)4] (1), which was isolated in excellent yield and crystallized in acetonitrile as the ion pair complex [Ul2(MeCN)7][Ul6] (2). Compound 1 was transformed in pyridine (py) and dimethylformamide (dmf) into the Lewis base adducts [Ul4(py)3] (3) and [Ul4(dmf)6] (4). Crystals of 3 and [U(dmf)9]l4 (5) were obtained by slow diffusion of diethyl ether into pyridine or dmf solutions of 1; compound 5 is the first tetracationic {U4+} entity to have been crystallographically characterized.     

Homoleptic tris(dithiolene) and tetrakis(dithiolene) complexes of uranium(IV)

Reaction of UCl4 with 3 or 4 mol equiv of Na2dddt (dddt = 5,6-dihydro-1,4-dithiine-2,3-dithiolate) in THF afforded the first example of a tetrakis(dithiolene) metal compound, [Na4(THF)8U(dddt)4](infinity) (1). The red crystals of 1 are composed of infinite zigzag chains in which Na2(micro-THF)3 fragments ensure the linking of Na2(THF)5U(dddt)4 moieties; the uranium atom is in a dodecahedral environment of eight sulfur atoms. Treatment of UCl4 with 3 mol equiv of Na2dddt in pyridine gave a mixture of tris- and tetrakis(dithiolene) compounds. After addition of 18c6 (18-crown-6), only the tris(dithiolene) complex was obtained and crystallized as orange crystals of [Na(18c6)(py)2]2[U(dddt)3].2py (2.2py) in which the isolated [U(dddt)3]2- anion adopts a slightly distorted trigonal prismatic configuration. A few red crystals of the unsolvated complex 2 and the trinuclear anionic compound [Na(18c6)(py)2]3[Na{U(dddt)3}2] (3) were also obtained along with orange crystals of 2.2py. All the tris(dithiolene) compounds exhibit large folding of the dddt ligand and significant interaction between the C=C double bond and the metal center.     

Half-sandwich o-N,N-dimethylaminobenzyl complexes over the full size range of group 3 and lanthanide metals. synthesis, structural characterization, and catalysis of phosphine P--H bond addition to carbodiimides

The acid-base reactions between the rare-earth metal (Ln) tris(ortho-N,N-dimethylaminobenzyl) complexes [Ln(CH2C(H4NMe2-o)3] with one equivalent of the silylene-linked cyclopentadiene-amine ligand (C5Me4H)SiMe2NH(C6H2Me3-2,4,6) afforded the corresponding half-sandwich aminobenzyl complexes [{Me2Si(C5Me4)(NC6H2Me3-2,4,6)}Ln(CH2C6H4NMe2-o)(thf)] (2-Ln) (Ln=Y, La, Pr, Nd, Sm, Gd, Lu) in 60-87 % isolated yields. The one-pot reaction between ScCl(3) and [Me2Si(C5Me4)(NC6H2Me3-2,4,6)]Li2 followed by reaction with LiCH2C6H4NMe2-o in THF gave the scandium analogue [{Me2Si(C5Me4)(NC6H2Me3-2,4,6)}Sc(CH2C6H4NMe2-o)] (2-Sc) in 67 % isolated yield. 2-Sc could not be prepared by the acid-base reaction between [Sc(CH2C6H4NMe2-o)3] and (C5Me4H)SiMe2NH(C6H2Me3-2,4,6). These half-sandwich rare-earth metal aminobenzyl complexes can serve as efficient catalyst precursors for the catalytic addition of various phosphine P--H bonds to carbodiimides to form a series of phosphaguanidine derivatives with excellent tolerability to aromatic carbon-halogen bonds. A significant increase in the catalytic activity was observed, as a result of an increase in the metal size with a general trend of La>Pr, Nd>Sm>Gd>Lu>Sc. The reaction of 2-La with 1 equiv of Ph2PH yielded the corresponding phosphide complex [{Me2Si(C5Me4)(NC6H2Me3-2,4,6)}La(PPh2)(thf)2] (4), which, on recrystallization from benzene, gave the dimeric analogue [{Me2Si(C5Me4)(NC6H2Me3-2,4,6)}La(PPh2)]2 (5). Addition of 4 or 5 to iPrN=C=NiPr in THF yielded the phosphaguanidinate complex [{Me2Si(C5Me4)(NC6H2Me3-2,4,6)}La{iPrNC(PPh2)NiPr}(thf)] (6), which, on recrystallization from ether, afforded the ether-coordinated structurally characterizable analogue [{Me2Si(C5Me4)(NC6H2Me3-2,4,6)}La{iPrNC(PPh2)NiPr}(OEt2)] (7). The reaction of 6 or 7 with Ph2PH in THF yielded 4 and the phosphaguanidine iPrN=C(PPh2)NHiPr (3a). These results suggest that the catalytic formation of a phosphaguanidine compound proceeds through the nucleophilic addition of a phosphide species, which is formed by the acid-base reaction between a rare-earth metal o-dimethylaminobenzyl bond and a phosphine P--H bond, to a carbodiimide, followed by the protonolysis of the resultant phosphaguanidinate species by a phosphine P--H bond. Almost all of the rare earth complexes reported this paper were structurally characterized by X-ray diffraction studies.     

Mononuclear and dinuclear complexes with a [Ru(tBu2PCH2CH2PtBu2)(CO)] core

Thermolysis of solid [Ru(d(t)bpe)(CO)2Cl2](2, d(t)bpe =(t)Bu2PCH2CH2P(t)Bu2) under vacuum affords the five-coordinate complex [Ru(d(t)bpe)(CO)Cl2] (4), which was shown by X-ray crystallography to contain a weak remote agostic interaction. In solution, 4 can be readily trapped by CO, CH3CN or water to give [Ru(d(t)bpe)(CO)(L)Cl2](L = CO, 2; L = CH3CN, 6; L = H2O, 7). Reaction of 4 with AgOTf/H2O yields the tris-aqua complex [Ru(d(t)bpe)(CO)(H2O)3](OTf)2 (8), which has been structurally characterised and probed in solution by pulsed-gradient spin echo (PGSE) NMR spectroscopy. The water ligands in 8 are labile and easily substituted to give [Ru(d(t)bpe)(CO)(NCCH3)3](OTf)2 (10) and [Ru(d(t)bpe)(CO)(DMSO)3](OTf)2 (11). In the presence of CO, the tris-aqua complex undergoes water-gas shift chemistry with formation of the cationic hydride species [Ru(d(t)bpe)(CO)3H](OTf) (12) and CO2. X-Ray crystal structures of complexes 2, 4, 6, 8 and 11-12 are reported along with those for [{Ru(d(t)bpe)(CO)}2(mu-Cl)2(mu-OTf)](OTf) (3), [{Ru(d(t)bpe)(CO)}2(mu-Cl)3][Ru(d(t)bpe)(CO)Cl3](5) and [Ru(d(t)bpe)(CO)(H2O)2(OTf)](OTf)(9).     

Reduction of an eta2-iminoacyl ligand to eta2-iminium enabled by adjacent carbon monoxide ligand replacement with a variable electron donor alkyne ligand in a cationic Tungsten(II) bis(acetylacetonate) complex

Cationic iminoacyl-carbonyl tungsten complexes of the type [W(CO) (eta (2)-MeNCR)(acac) 2] (+) (acac = acetylacetonate; R = Ph ( 1a), Me ( 1b)) easily undergo thermal substitution of CO with two-electron donors to yield [W(L)(eta (2)-MeNCR)(acac) 2] (+) (L = tert-butylisonitrile [R = Ph ( 2a), Me ( 2b)], 2,6-dimethylphenylisonitrile [R = Me ( 2c)], triphenylphosphine [R = Ph ( 3a), Me ( 3c)], and tricyclohexylphosphine [R = Ph ( 3b)]). Tricyclohexylphosphine complex 3b exhibits rapid, reversible phosphine ligand exchange at room temperature on the NMR time scale. Photolytic replacement of carbon monoxide with either phenylacetylene or 2-butyne occurs efficiently to form [W(eta (2)-alkyne)(eta (2)-MeNCR)(acac) 2] (+) complexes ( 5a- d) with a variable electron donor eta (2)-alkyne paired with the eta (2)-iminoacyl ligand in the W(II) coordination sphere. PMe 3 adds to 1a or 5b to form [W(L)(eta (2)-MeNC(PMe 3)Ph)(acac) 2] (+) [L = CO ( 4), MeCCMe ( 6)] via nucleophilic attack at the iminoacyl carbon. Addition of Na[HB(OMe) 3] to 5b yields W(eta (2)-MeCCMe)(eta (2)-MeNCHPh)(acac) 2, 8, which exhibits alkyne rotation on the NMR time scale. Addition of MeOTf to 8 places a second methyl group on the nitrogen atom to form an unusual cationic eta (2)-iminium complex [W(eta (2)-MeCCMe)(eta (2)-Me 2NCHPh)(acac) 2][OTf] ( 9[OTf], OTf = SO 3CF 3). X-ray structures of 2,6-dimethylphenylisonitrile complex 2c[BAr' 4 ], tricyclohexylphosphine complex 3b[BAr' 4 ], and phenylacetylene complex 5a[BAr' 4 ] confirm replacement of CO by these ligands in the [W(L)(eta (2)-MeNCR)(acac) 2] (+) products. X-ray structures of alkyne-imine complexes 6[BAr' 4 ] and 8 show products resulting from nucleophilic addition at the iminoacyl carbon, and the X-ray structure of 9[BAr' 4 ] reflects methylation at the imine nitrogen to form a rare eta (2)-iminium ligand.     

Synthesis and reactivity of mono(amidinate) organoiron(II) complexes

The mono(amidinate) iron(ii) ferrate complex [{PhC(NAr)(2)}FeCl(micro-Cl)Li(THF)(3)] (1, Ar = 2,6-iPr(2)C(6)H(3)) was prepared and was found to undergo ligand redistribution in non-coordinating solvents to give the homoleptic [{PhC(NAr)(2)}(2)Fe] (2) as the only isolable product. Reaction of with alkylating agents also induces this redistribution, but the presence of pyridine allows isolation of the four-coordinate 14 VE monoalkyl complex [{PhC(NAr)(2)}FeCH(2)SiMe(3)(py)] (4). Generation of the 12 VE alkyl via pyridine abstraction from 4 by B(C(6)F(5))(3) again induced ligand redistribution. Attempts to trap a 12 VE alkyl species with CO led to the isolation of a dimeric Fe(0)-Li-ferrate complex (3) with a carbamoyl ligand, derived from CO insertion into the iron-amidinate bond.     

Syntheses, X-ray crystal structures, and magnetic properties of novel linear M2[II]U[IV] complexes (M=Co, Ni, Cu, Zn)

Attempts to prepare heterobimetallic complexes in which 3d and uranium magnetic ions are associated by means of the Schiff bases H(2)L(i) derived from 2-hydroxybenzaldehyde or 2-hydroxy-3-methoxybenzaldehyde were unsuccessful because of ligand transfer reactions between [ML(i)] (M=Co, Ni, Cu) and UCl(4) that led to the mononuclear Schiff base complexes of uranium [UL(i)Cl(2)]. The crystal structure of [UL(3)Cl(2)(py)(2)] [L(3)=N,N'-bis(3-methoxysalicylidene)-ethylenediamine; py=pyridine] was determined. The hexadentate Schiff base ligand N,N'-bis(3-hydroxysalicylidene)-2,2-dimethyl-1,3-propanediamine (L) was useful for the synthesis of novel trinuclear complexes of the general formula [[ML(py)](2)U] (M=Co, Ni, Zn) or [[CuL(py)]M'[CuL]] (M'=U, Th, Zr) by reaction of [M(H(2)L)] with [M'(acac)(4)] (acac=MeCOCHCOMe). The crystal structures of the Co(2)U, Ni(2)U, Zn(2)U, Cu(2)U, and Cu(2)Th complexes show that the two ML fragments are orthogonal, being linked to the central actinide ion by the two pairs of oxygen atoms of the Schiff base ligand. In each compound, the UO(8) core exhibits the same dodecahedral geometry, and the three metals are linear. The magnetic study indicated that the two Cu(2+) ions are not coupled in the Cu(2)Zr and Cu(2)Th compounds. The magnetic behavior of the Co(2)U, Ni(2)U, and Cu(2)U complexes was compared with that of the Zn(2)U derivative, in which the paramagnetic 3d ion was replaced with the diamagnetic Zn(2+) ion. A weak antiferromagnetic coupling was observed between the Ni(2+) and the U(4+) ions, while a ferromagnetic interaction was revealed between the Cu(2+) and U(4+) ions.     

Synthesis of (C5Me5)2(C5Me4H)UMe, (C5Me5)2(C5H5)UMe, and (C5Me5)2UMe[CH(SiMe3)2] from cationic metallocenes for the evaluation of sterically induced reduction

To probe the correlation of unusual (C5Me5)(1-) reactivity with steric crowding in complexes such as (C5Me5)3UMe and (C5Me5)3UCl, slightly less crowded (C5Me5)2(C5Me4H)UX analogues (X = Me, Cl) were synthesized and their reactivity was evaluated. The utility of the cationic precursors [(C5Me5)2UMe](1+), 1, and [(C5Me5)2UCl](1+), 2, in the synthesis of (C5Me5)2(C5Me4H)UMe, 3, and (C5Me5)2(C5Me4H)UCl, 4, was also explored. Since the use of precursor [(C5Me5)2UMe][MeBPh3], 1a, is complicated by the equilibrium between 1a and (C5Me5)2UMe2/BPh3, the reactivity of [(C5Me5)2UMe(OTf)]2, 1b, (OTf = O3SCF3) prepared from (C5Me5)2UMe2 and AgOTf, was also studied. Both 1a and 1b react with KC5Me4H to form 3. Complex 4 readily forms by addition of KC5Me4H to [(C5Me5)2UCl][MeBPh3], generated in situ from (C5Me5)2UMeCl and BPh3. Complex 1b was preferred to 1a for the synthesis of (C5Me5)2(C5H5)UMe, 5, and (C5Me5)2UMe[CH(SiMe3)2], 6, from KC5H5 and LiCH(SiMe3)2, respectively. Complex 6 is the first example of a mixed alkyl uranium metallocene complex. Sterically induced reduction (SIR) reactivity was not observed with 3-6 although the methyl displacements from the (C5Me5)(1-) ring plane for 3 are the closest observed to date to those of SIR-active complexes. The (1)H NMR spectra of 3 and 4 are unusual in that all of the (C5Me4H)(1-) methyl groups are inequivalent. This structural rigidity is consistent with density-functional theory calculations.     

General synthesis of (salen)ruthenium(III) complexes via N...N coupling of (salen)ruthenium(VI) nitrides

Reaction of [Ru (VI)(N)(L (1))(MeOH)] (+) (L (1) = N, N'-bis(salicylidene)- o-cyclohexylenediamine dianion) with excess pyridine in CH 3CN produces [Ru (III)(L (1))(py) 2] (+) and N 2. The proposed mechanism involves initial equilibrium formation of [Ru (VI)(N)(L (1))(py)] (+), which undergoes rapid N...N coupling to produce [(py)(L (1))Ru (III) N N-Ru (III)(L (1))(py)] (2+); this is followed by pyridine substituion to give the final product. This ligand-induced N...N coupling of Ru (VI)N is utilized in the preparation of a series of new ruthenium(III) salen complexes, [Ru (III)(L)(X) 2] (+/-) (L = salen ligand; X = H 2O, 1-MeIm, py, Me 2SO, PhNH 2, ( t )BuNH 2, Cl (-) or CN (-)). The structures of [Ru (III)(L (1))(NH 2Ph) 2](PF 6) ( 6), K[Ru (III)(L (1))(CN) 2] ( 9), [Ru (III)(L (2))(NCCH 3) 2][Au (I)(CN) 2] ( 11) (L (2) = N, N'-bis(salicylidene)- o-phenylenediamine dianion) and [N ( n )Bu 4][Ru (III)(L (3))Cl 2] ( 12) (L (3) = N, N'-bis(salicylidene)ethylenediamine dianion) have been determined by X-ray crystallography.     

Oxo- and imidovanadium complexes incorporating methylene- and dimethyleneoxa-bridged calix[3]- and -[4]arenes: synthesis, structures and ethylene polymerisation catalysis

Reaction of [V(X)(OR)3] (X=O, Np-tolyl; R=Et, nPr or tBu) with p-tert-butylhexahomotrioxacalix[3]areneH3, LH3, affords the air-stable complexes [{V(X)L}n] (X=O, n=1 (1); X=Np-tolyl, n=2 (2)). Alternatively, 1 is readily available either from interaction of [V(mes)3THF] with LH3, and subsequent oxidation with O2 or upon reaction of LLi3 with [VOCl3]. Reaction of [V(Np-tolyl)(OtBu)3] with 1,3-dimethylether-p-tert-butylcalix[4]areneH2, Cax(OMe)2(OH)2, afforded [{VO(OtBu)}2(mu-O)Cax(OMe)2(O)2].2 MeCN (42 MeCN), in which two vanadium atoms are bound to just one calix[4]arene ligand; the n-propoxide analogue of 4, namely [{VO(OnPr)}2(mu-O)Cax(OMe)2(O)2].1.5 MeCN (51.5 MeCN), has also been isolated from a similar reaction using [V(O)(OnPr)3]. Reaction of [VOCl3], LiOtBu, (Me3Si)2O and Cax(OMe)2(OH)2 gave [{VO(OtBu)Cax(OMe)2(O)2}2Li4O2].8 MeCN (68 MeCN), in which an Li4O4 cube (two of the oxygen atoms are derived from the calixarene ligands) is sandwiched between two Cax(OMe)2(O)2. The reaction between [V(Np-tolyl)(OtBu)3] and Cax(OMe)2(OH)2, afforded [V(Np-tolyl)(OtBu)2Cax(OMe)2(O)(OH)]5 MeCN (75 MeCN), in which two tert-butoxide groups remain bound to the tetrahedral vanadium atom, which itself is bound to the calix[4]arene through only one phenolic oxygen atom. Reaction of p-tert-butylcalix[4]areneH4, Cax(OH)4 and [V(Np-tolyl)(OnPr)3] led to loss of the imido group and formation of the dimeric complex [{VCax(O)4(NCMe)}2].6 MeCN (86 MeCN). Monomeric vanadyl oxo- and imidocalix[4]arene complexes [V(X)Cax(O)3(OMe)(NCMe)] (X=O (11), Np-tolyl (12)) were obtained by the reaction of the methylether-p-tert-butylcalix[4]areneH3, Cax(OMe)(OH)3, and [V(X)(OR)3] (R=Et or nPr). Vanadyl calix[4]arene fragments can be linked by the reaction of 2,6-bis(bromomethyl)pyridine with Cax(OH)4 and subsequent treatment with [VOCl3] to afford the complex [{VOCax(O)4}2(mu-2,6-(CH2)2C5H3N)].4 MeCN (134 MeCN). The compounds 1-13 have been structurally characterised by single-crystal X-ray diffraction. Upon activation with methylaluminoxane, these complexes displayed poor activities, however, the use of dimethylaluminium chloride and the reactivator ethyltrichloroacetate generates highly active, thermally stable catalysts for the conversion of ethylene to, at 25 degrees C, ultra-high-molecular-weight (>5, 500,000), linear polyethylene, whilst at higher temperature (80 degrees C), the molecular weight of the polyethylene drops to about 450,000. Using 1 and 2 at 25 degrees C for ethylene/propylene co-polymerisation (50:50 feed) leads to ultra-high-molecular-weight (>2,900,000) polymer with about 14.5 mol% propylene incorporation. The catalytic systems employing the methyleneoxa-bridged complexes 1 and 2 are an order of magnitude more active than the bimetallic complexes 5 and 13, which, in turn, are an order of magnitude more active than pro-catalysts 8, 11 and 12. These differences in activity are discussed in terms of the structures of each class of complex.     

Divalent lanthanide complexes supported by the bridged bis(amidinates) L Me3SiN(Ph)CN(CH2)3NC(Ph)NSiMe3]: synthesis, molecular structures and one-electron-transfer reactions

Metathesis reactions of YbI(2) with Li(2)L (L = Me(3)SiN(Ph)CN(CH(2))(3)NC(Ph)NSiMe(3)) in THF at a molar ratio of 1:1 and 1:2 both afforded the Yb(II) iodide complex [{YbI(DME)(2)}(2)(μ(2)-L)] (1), which was structurally characterized to be a dinuclear Yb(II) complex with a bridged L ligand. Treatment of EuI(2) with Li(2)L did not afford the analogous [{EuI(DME)(2)}(2)(μ(2)-L)], or another isolable Eu(II) complex, but the hexanuclear heterobimetallic cluster [{Li(DME)(3)}(+)](2)[{(EuI)(2)(μ(2)-I)(2)(μ(3)-L)(2)(Li)(4)}(μ(6)-O)](2-) (2) was isolated as a byproduct in a trace yield. The rational synthesis of cluster 2 could be realized by the reaction of EuI(2) with Li(2)L and H(2)O in a molar ratio of 1:1.5:0.5. The reduction reaction of LLnCl(THF)(2) (Ln = Yb and Eu) with Na/K alloy in THF gave the corresponding Ln(II) complexes [Yb(3)(μ(2)-L)(3)] (3) and [Eu(μ(2)-L)(THF)](2) (4) in good yields. An X-ray crystal structure analysis revealed that each L in complex 3 might adopt a chelating ligand bonding to one Yb atom and each Yb atom coordinates to an additional amidinate group of the other L and acts as a bridging link to assemble a macrocyclic structure. Complex 4 is a dimer in which the two monomers [Eu(μ(2)-L)(THF)] are connected by two μ(2)-amidinate groups from the two L ligands. Complex 3 reacted with CyN═C═NCy and diazabutadienes [2,6-(i)Pr(2)C(6)H(3)N═CRCR═NC(6)H(3)(i)Pr(2)-2,6] (R═H, CH(3)) (DAD) as a one-electron reducing agent to afford the corresponding Yb(III) derivatives: the complex with an oxalamidinate ligand [LYb{(NCy)(2)CC(NCy)(2)}YbL] (5) and the complexes containing a diazabutadiene radical anion [LYb((i)Pr(2)C(6)H(3)NCRCRNC(6)H(3)(i)Pr(2))] (R = H (6), R = CH(3) (7)). Complexes 5-7 were confirmed by an X-ray structure determination.     

Practical synthetic routes to solvates of U(OTf)3: X-ray crystal structure of [U(OTf)3(MeCN)3]n, a unique U(III) coordination polymer

The reaction of UH3 or U metal with triflic acid results in the formation of a mixture of species including U(OTf)4 and leads to the reproducible isolation of the mononuclear U(IV) hydroxo complex [U(OTf)3(OH)(py)4] (1) and the U(IV) dinuclear mu-oxo-complex [{U(OTf)2(py)3}2{mu-O}{mu-OTf}2] (2). The X-ray crystal structures of these complexes have been determined. Analytically pure complex 1 can be prepared in a 17-27% yield providing a good precursor for the synthesis and study of the reactivity of the hydroxo complexes with different coordination environments. Two practical synthetic methods for the preparation of Lewis base adducts of U(OTf)3 are described. Analytically pure [U(OTf)3(py)4] (4) was easily and reproducibly prepared (50-60% yield) by protonolysis of the amide U{N(SiMe3)2}3 with pyridinium triflate in pyridine. Salt metathesis of UI3(thf)4 with potassium triflate in acetonitrile resulted in the complete substitution of the iodide counterions by triflate producing the acetonitrile solvate [U(OTf)3(MeCN)3]n (3). The solid-state structure of 3 shows the formation of a unique U(III) coordination polymer in which the metal ions are connected by three triflates acting as bidentate bridging ligands to form a 1D chain.     

The first acetimine gold(I) and gold(III) complexes and the first acetonine complexes

Ketimino(phosphino)gold(I) complexes of the type [Au[NR=C(Me)R']L]X (X = ClO4, R = H, L = PPh3, R'=Me (la), Et (2a); L=PAr3 (Ar=C6H4OMe-4), R'=Me (1b), Et (2b); L=PPh3, R=R'=Me (3); X= CF3SO3 (OTf), L=PPh3, R=R'=Me (3'); R=Ar, R'=Me (4)) have been prepared from [Au(acac)L] (acac = acetyl acetonate) and ammonium salts [RNH3]X dissolved in the appropriate ketone MeC(O)R'. Complexes [Au(NH=CMe2)2]X (X = C1O4 (6), OTf (6')) were obtained from solutions of [Au(NH3)2]X in acetone. The reaction of 6 with PPN[AuCl2] or with PhICl2 gave [AuCl(NH=CMe2)] (7) or [AuCI2(NH=CMe2)2]ClO4 (8), respectively. Complex 7 was oxidized with PhICl2 to give [AuCl3(NH=CMe2)] (9). The reaction of [AuCl(tht)] (tht = tetrahydrothiophene), NaClO4, and ammonia in acetone gave [Au(acetonine)2]ClO4 (10) (acetonine = 2,2,4,4,6-pentamethyl-2,3,4,5-tetrahydropyrimidine) which reacted with PPh3 or with PPN[AuCl2] to give [Au(PPh3)(acetonine)]ClO4 (11) or [AuCl(acetonine)] (12), respectively. Complex 11 reacts with [Au(PPh3)(Me2CO)]ClO4 to give [(AuPPh3)2(mu-acetonine)](ClO4)2 (13). The reaction of AgClO4 with acetonine gave [Ag(acetonine)(OClO3)] (14). The crystal structures of [Au(NH2Ar)(PPh3)]OTf (5), 6' and 10 have been determined.